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NlTED STATES a'rnnr rricn.

CHARLES E. SORIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERN ELECTRIC COMPANY, OF SAME PLACE.

TELEPHONE-ClRGUIT.

SPECIFICATION forming part of Letters Patent N0. 597,786, dated January 25, 1898.

A plication filed Decemlier 18, 1896. Serial No. 616,128. (No model.)

To (1955 whom it may concern: appliances are in a sense complementary to Beitknown that I, CHARLES E. SORIBNER, a each other in function. citizen of the United States, residing at Chi- It is found that in a system thus provided cago, in the county of Cook and State of Illi-. with condensers the telephonic transmission nois, have invented a certain new and useful of speech between the stations is effected with 5 5 Improvement in Telephone-Circuits, (Case remarkable loudness and distinctness of ar- No. e33 of which the following is a full, clear, ticulation.

concise, and exact description, reference be- It may be mentioned that in ordinary exing had to the accompanying drawing, formchange practice the direct or conductive coning a part of this specification. nection of twolines with each other, the source My invention concerns the supply of curof current being placed in a bridge of the rent for transmiHing-telephones at substalines, is not attended with satisfactory results, tions from a centrally located source of ensince in the case of a line of low resistance ergy. It is designed to improve the articulaconnected with one of high resistance the for- 15 tion and increase the efficiency of transmismer diverts the greater port-ion of the current sion in a certain well-known mode of supply supplied to the lines from the other, and hence in common use. prevents satisfactory transmission from the The mode of current-s11 pply referred to conlatter. sists in connecting the line conductors'of two The attached drawing illustrates the inven- 2o united lines with the opposite poles of a cention. This represents two substations A and trally-locatedsource of current, two mutually- B, united by line-circuits and connected after inductive windings of a repeating-coil being the manner of my invention with a source of interposed in the line conductors, one in the current at an intermediate point. Ateach circuit leading to each of the stations. Ourof the substations is placed a transmitting- 2 5 rent flows from the central supply-battery telephone aandareceiving-telephone a. The through a winding of the repeating-coil to instruments of station A are included in the each of the lines and finds circuit through the .line-circuit 1 2, which extends to a central transmitting-telephone at the corresponding office 0., Those at station B are contained in station. Variations in the current produced a similar line-circuit 3 4, also extending to 30 by variations in the resistance of one of the the same central ofiice. The line conductors 8o transmitt-irig-telephones are propagated into 1 and 3 are connected with the opposite plates the circuit of the other line through the meof a condenser b. W'ires 2 and at are likewise dium of the repeating-coil. It is found in connected with the condenser Z2. Wires 1 practice, however, that the repeating-coil imand 3 are further united through two helices 3 5 pairs the distinct-mess of articulation and the c and c of a repeating-coil, wires 2 and 4 beefficiency of transmission to some extent, posing likewise united through other windings sibly by suppressing the undulations of high c and 0 These windings are for convenience period to a greater extent than those of lower placed upon the same core. It is only essenfrcquency. tial, however, that windings c and c and wind- 0 I have discovered that the natural charac- 'ings c and 0 shall be in inductive relation to 0 teristics of the articulation may be restored each other, respectively. The points of juncby connecting a condenser of suitable capaction of the windings c c and 0 c are united ity in a shunt or parallel circuit with the two by a conductor 5 in which a common source windings of the repeating-coil through which .of current-supply d is interposed.

45 the diiferent line conductors are united. Current from battery (Z flows out through The condenser appears to permit the propawinding 0 of the repeating-coil through line gation through it most readily of vibrations conductors 1 and 2 and returns through windof high frequency, thus supplying an efiicient ing c of the repeating-coil. Current for supmeans of propagating those overtones which plying the transmitting-telephone at station 50 the repeating-coil tends to suppress. The two B likewise finds circuit through windings c and c and line conductors 3 and 4. The current in either line is independent. of that in the other, the conductive connection of the lines with each other being interrupted at the condensers. Sounds made before either transmitter cause corresponding variations in the resistance in the transmitter, andhence create corresponding undulations in the current in the line-circuit. These undulations are in part propagated by static induction through the condensers b and 1) into the other line-circuit and in part by electromagnetic induction between the windings of the repeating-coil.

The condensers and repeating-coil may be associated with the connecting plugs and plug-circuit, by means of which it is customary to unite the lines of a telephone-exchange in a switchboard. I have not deemed it necessary to show the accessory apparatus, as it does not enter into the present invention.

I claim as my inventionl. I11 combination, a source of telephonic undulatory current and a receiving instrument therefor in a closed conducting-circuit, two windings of a repeating-coil serially included in the circuit, a conductor including a condenser in shunt of the windings of the repeating-coil, and a bridge uniting the point of junction of the windings of the repeatingcoil with the other side of the circuit, as described.

2. The combination with a source of telephonic undulatory current and a receiving instrument therefor at different stations, of

a closed circuit including the source of undulating current, another closed circuit including the receiving instrument, a winding of a repeating-coil in each of the circuits, said windings being in inductive relation to each other, and conductors including condensers uniting the different circuits, as described.

3. The combination with a transmitting telephone and a receiving-telephone at different stations, of a circuit including the instruments at the diiferent stations, two windings of a repeating-coil included serially in the circuit, a bridge of the circuit connected with the point of junction of the said windings, a source of current in the bridge, a conductor in shunt of the said serially-connected windings, and a condenser interposed in the shunt, as described.

4. The combination with a transmittingtelephone and a receiving-telephone at each of two stations and a circuit including the instruments of both stations, of two windings of a repeating-coil included serially in each of the line conductors of the said circuit. a bridge of the circuit from points intermediate of the said windings and a source of current included in the bridge, a shunt about each pair of serially-connected windings, and a condenserin each of said shunts, as described.

In witness whereof I hereunto subscribe my name this 3d day of October, A. D. 1896.

CHARLES E. SCRIBNER. WVit-nesses:

ELLA EDLER, PEARL CLENDENING. 

